|Publication number||US5483360 A|
|Application number||US 08/254,629|
|Publication date||Jan 9, 1996|
|Filing date||Jun 6, 1994|
|Priority date||Jun 6, 1994|
|Also published as||DE69512468D1, DE69512468T2, EP0687103A2, EP0687103A3, EP0687103B1|
|Publication number||08254629, 254629, US 5483360 A, US 5483360A, US-A-5483360, US5483360 A, US5483360A|
|Inventors||Robert J. Rolleston, Martin S. Maltz|
|Original Assignee||Xerox Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (6), Non-Patent Citations (16), Referenced by (107), Classifications (15), Legal Events (10)|
|External Links: USPTO, USPTO Assignment, Espacenet|
C,M,Y=A1(r,g,b)ŚLUT1(r,g,b)+A2(r,g,b)ŚLUT2(r,g,b)+A3(r,g,b).times.LUT3(r,g,b)+ . . . +AN(r,g,b)ŚLUTN(r,g,b)
A1+A2+A3 . . . +AN=1.
C,M,Y=A1(r,g,b)ŚLUT1(r,g,b)+A2(r,g,b)ŚLUT2(r,g,b)+A3(r,g,b).times.LUT3(r,g,b)+ . . . +AN(r,g,b)ŚLUTN(r,g,b)
A1+A2+A3 . . . +AN=1.
C,M,Y=A1(r,g,b)ŚLUT1(r,g,b)+A2(r,g,b)ŚLUT2(r,g,b)+A3(r,g,b).times.LUT3(r,g,b)+ . . . +AN(r,g,b)ŚLUTN(r,g,b)
A1+A2+A3 . . . +AN=1.
The present invention is directed towards compiling look up tables representative of printer characteristics, to enable the conversion of colors defined in a first color space to colors defined in a printer color space, and more particularly to a method of blending or combining the characteristics represented by such tables.
Cross reference is made to the following co-pending applications: U.S. Ser. No. 07/955,075, filed Oct. 1, 1992, entitled "Color Printer Calibration Architecture", by R. J. Rolleston et al. (assigned to the same assignee as the present application); U.S. Ser. No. 08/131,168, filed Oct. 4, 1993, entitled "Reduced Storage of Pre-Computed Difference Tables Used In Color Space Conversion", by R. J. Rolleston (assigned to the same assignee as the present application); U.S. Ser. No. 08/144,987, filed Oct. 29, 1993, entitled "Color Printer Calibration Test Pattern" by R. J. Rolleston et al. (assigned to the same assignee as the present application); U.S. Ser. No. 08/179,284, filed Jan. 10, 1994, entitled "Color Printer Calibration Architecture", by R. J. Rolleston et al. (assigned to the same assignee as the present application); and U.S. Ser. No. 08/223,494 filed Apr. 5, 1994, entitled, "Color Printer Calibration with Improved Color Mapping Linearity", by R. J. Rolleston, (assigned to the same assignee as the present application).
The following, patents are specifically incorporated by reference: U.S. Pat. No. 4,500,919 to Schreiber for its teachings of a color conversion system converting information from RGB to CMYK; U.S. Pat. No. 4,275,413 to Sakamoto for its teachings of tetrahedral interpolation between first and second color spaces; and U.S. Pat. No. 2,790,844 to Neugebauer disclosing the desirability of defining an image in a first standard color space prior to conversion of the image coordinates to a second printer based coordinate system. The following articles are also hereby incorporated by reference: Po-Chieh Hung, "Tetrahedral Division Technique Applied to Colorimetric Calibration for Imaging Media ", Annual Meeting IS&T, NJ, May, 1992, pp. 419-422; and Sigfredo I. Nin, et al., "Printing CIELAB Images on a CMYK Printer Using Tri-Linear Interpolation", SPIE Proceedings, Vol. 1670, 1992, pp. 316-324; and William J. Gordon et al., "Shepard's Method of `Metric Interpolation` applied to Bivariate and Multivariate Interpolation", Mathematics of Computation, Vol. 32, No. 141, January 1978, pp. 253-264 and P. Lancaster et al., "Surfaces Generated by Moving Least Squares Methods", Mathematics of Computation, Vol. 32, No. 155, July 1981, pp.141-158; and Pekka Laihanen, "Colour Reproduction Theory Based on the Principles of Colour Science", Advances in Printing Science and Technology, W. H. Banks ed., Pentech Press, London, 1988, pp. 1-36; and Pekka Laihanen, "Optimization of Digital Color Reproduction on the Basis of Visual Assessment of Reproduced Images", Proceedings of the SID, Vol 30. No. 3, 1989, pp. 183-190.
The generation of color documents can be thought of as a two step process: first, the generation of the image by means of scanning an original document with a color image input terminal or scanner or, alternatively, creating a color image on a work station operated in accordance with a color image creation program; and secondly, printing of that image with a color printer in accordance with the colors defined by the scanner or computer generated image. Scanner output is commonly transformed to a color space of tristimulus values, i.e., RGB (red-green-blue). Commonly, these values are a linear transformation of the standard XYZ coordinates of CIE color space, or a corrected transform of those values. In the case of computer generated images, colors defined by the user at the user interface of a workstation can be defined initially in color space of tristimulus values. These colors are defined independently of any particular device, and accordingly reference is made to the information as being "device independent".
Printers commonly have an output which can be defined as existing in a color space called CMYK (cyan-magenta-yellow-key or black) which is uniquely defined for the printer by its capabilities and colorants. Printers operate by the addition of multiple layers of ink or colorant in layers to a page. The response of the printer tends to be relatively non-linear. These colors are defined for a particular device, and accordingly reference is made to the information as being "device dependent". Thus, while a printer receives information in a device independent color space, it must convert that information to print in a device dependent color space, which reflects the gamut or possible range of colors of the printer. Printers may print with colors beyond CMYK, for a variety of special purposes or to extend the device gamut.
The desirability of operating in a device independent color space with subsequent conversion to a device dependent color space is well known, as shown by U.S. Pat. No. 4,500,919 to Schreiber and U.S. Pat. No. 2,790,844 to Neugebauer, and U.S. Pat. No. 4,275,413 to Sakamoto. There are many methods of conversion between color spaces, all of which begin with the measurement of printer response to certain input values. Commonly, a printer is driven with a set of input values reflecting color samples throughout the printer gamut, the color samples are printed in normal operation of the printer. As previously noted, most printers have non-linear response characteristics.
In U.S. Pat. No. 4,275,413 to Sakamoto, the information derived is placed into look up tables, stored in a memory, perhaps ROM memory or RAM memory where the look up table relates input color space to output color space. The look up table is commonly a three dimensional table since color is defined with three variables. In RGB space, at a scanner or computer, space can be defined as three dimensional with black at the origin of a three dimensional coordinate system 0, 0, 0, and white at the maximum of a three dimensional coordinate system which an 8-bit system, would be located at 255, 255, 255. Each of the three axes radiating from the origin point therefore respectively define red, green, and blue. In the 8-bit system suggested, there will be, however, over 16 million possible colors (2563). There are clearly too many values for a 1:1 mapping of RGB to CMY. Therefore, the look up tables consist of a set of values which could be said to be the intersections for corners of a set of cubes mounted on top of one another. Colors falling within each cubic volume can be interpolated from the measured values, through many methods including tri-linear interpolation, tetrahedral interpolation, polynomial interpolation, linear interpolation, and any other interpolation method depending on the desired accuracy of the result.
It would be very easy to index device dependent color values or specifications to device independent color specifications, but that is not the requirement. Instead, device independent specifications must be mapped to device dependent specifications. Several problems arise. Of course, the primary problem is that the printer response is not a linear response. A second problem is that the color space, and therefore the coordinates defined in the color space must be maintained as a uniform grid for maximum efficiency of some interpolation methods.
Accordingly, a multi-dimensional look up table (LUT) may be constructed which puts device independent input values into a predictable grid pattern. One method of accomplishing this requirement is by an interpolation process which derives a value at a desired location as a function of all (or a significant set) of measured color values. This method of interpolation is known as Shepard's Method (see, for example "Shepard's Method of `Metric Interpolation` to Bivariate and Multivariate Interpolation" by W. Gordon and J. Wixom, Mathematics of Computation, Vol. 32, No. 141, January 1978, pp. 253-264). Shepard's Method suggests that a vector can be thought of as defining the difference between an asked-for color which was directed to a printer in the printed color. Then, for any other point in color space which is desired, that point can be thought of as a vector quantity, derived by averaging over the space all the vectors, each vector weighted by a function which decreases its effect on the vector as that vector is further and further away from the point coloring question. In one useful formula, each vector is weighted by a function of 1/d 4.
Alternatively the method of Po-Chieh Hung, "Colorimetric Calibration for Scanners and Media", SPIE, Vol. 1448, Camera and Input Scanner System, (1991), describes a method of inverse tetrahedral interpolation, to the same effect as the described Shepard's Method.
In one actual calibration test, it was noted that the weighted averaging technique produced a table which gave good color reproduction in one region of color space (the light colors), but not in another (the dark colors). The tetrahedral inversion technique was just the complement of this, i.e., it gave good color reproduction where the weighted average technique did not (the dark colors), and gave poorer color reproduction of colors where the weighted average technique gave good color reproduction (the light colors).
Similar to the above problem, it has been noted that often, after a change in process parameters due to time, change of materials, refilling toner, etc., a change in calibration is required only in a portion of the overall color gamut of a printer. Recalibration of the entire space is costly in terms of processing time. It would be desirable to only recalibrate a portion of the color space, or alternatively, to use the best portions of the color space mapping.
The references cited herein are incorporated by reference for their teachings.
In accordance with the invention there is provided a method generating a color space transform look up table derived from printer calibration measurements using separate table generations to produce the functionality of a single look up table.
In accordance with the invention, a color printer responsive to printer signals to deposit printer colorants on a medium in accordance with printer signals received, is calibrated by operating the color printer with printer signals selected to cause the printer to print color samples on the medium; measuring the color samples to determine a first colorimetric response of the printer to the printer signals using the first measured colorimetric response to generate a first mapping of colorimetric values to printer signals; using the first measured colorimetric response or a subsequent measured colorimetric response to generate at least one additional mapping of colorimetric values to printer signals; storing the first and additional mappings in a color conversion memory producing printer signals as a function of the first and additional mappings stored in the color conversion memory to convert color definitions from a first color space to the printer signals suitable for producing a corresponding response at the color.
In accordance with one aspect of the invention, the selected areas or portions of two (or more) look up tables mapping colorimetric values to color printer responses are blended. The output response for any colorimetric description from the blended tables is a linear combination of the output responses of the separate tables, where the linear function is adjusted as a function of position of the colorimetric description within colorimetic color space.
In accordance with another aspect of the invention, the second look up table may differ from the first look up table due to the creation method although using the same set of color samples, or the second look up table may differ from the first look up table due to using a different set of color samples.
These and other aspects of the invention will become apparent from the following descriptions used to illustrate a preferred embodiment of the invention read in conjunction with the accompanying drawings in which:
FIGS. 1 and 2 together illustrate an overall system block diagram showing a color printing system in which the present invention might find use; and
FIG. 3 illustrates the blended mapping described.
Referring now to the drawings where the showings are for the purpose of describing an embodiment of the invention and not for limiting same, a basic system for carrying out the present invention is shown in FIG. 1. In a system, a scanner 10, such as perhaps the color scanner available in the Xerox 5775 digital color copiers, which can be calibrated to produce a set of digital colorimetric or device independent data describing an original image 12, rendered in colors RO, GO,BO, which, by definition, can be defined in terms of a colorimetric rgb space. Resulting from the scanning operation is a set of scanner image signals Rs, Gs, Bs, defined in device dependent scanner terms. Incorporated into the scanner or another processing path is a post-scanning processor 14, which provides correction of scanner image signals Rs, Gs, Bs to colorimetric terms, Rc, Gc, Bc, typically digital in nature. The values may be in terms of CIE color space (rgb), or the L*a*b*, or luminance-chrominance space (LC1 C2). A color space transform, indicated by block 20, such as that described in U.S. Pat. No. 4,275,413 to Sakamoto, is used to convert the device independent data to device dependent data. The output of color space transform 20 is the image defined in terms of a device dependent space, or printer colorant signals Cp, Mp, Yp, Kp that will be used to drive a printer 30. In one possible example, the colorant signals represent the relative amounts of cyan, magenta, yellow, and black toners to be deposited over a given area in an electrophotographic printer, such as, again, Xerox 5775 digital color copier. The printed output image may be said to be defined in terms of Rp,Gp,Bp, which are hoped to have a relationship with Ro,Go,Bo such that the printed output image has a color that is colorimetrically similar to the original image, although that similarity is ultimately dependent upon the gamut of the printing device.
With reference now to FIG. 2, and color space transformation and color correction 20, initially, Rc, Gc, Bc color signals are directed to a lookup table and interpolation device 40, which provides a three dimensional look up arrangement in a device memory such as a RAM or other addressable memory device, which will meet speed and memory requirements for a particular device. Color signals Rc, Gc, Bc are processed to generate address entries to a table therein which stores a set of transform coefficients with which the signals Rc, Gc, Bc may be processed to convert them to Cx, Mx, Yx colorant signals or any multi-dimensional output color space including but not limited to CMYK or spectral data. Values which are not mapped may be determined through interpolation. As described in U.S. Pat. No. 5,305,119 by Rolleston, entitled "Color Printer Calibration Architecture", black addition for under color removal and gray balance processing may also be combined into the color space transform element. Although these features are not required, they are desirable and are illustrated herein. When we refer to colorimetric spaces, we are referring to spaces which are transforms of CIE XYZ space (1931). When we refer to device dependent space, we refer to a color space which is defined only in terms of operation of the device using it. While many color spaces have three dimensions, it is possible to have color spaces with less than three dimensions or more than three dimensions, and likewise, it is possible for printers to use less than three colorants or more than four colorants.
It will no doubt be recognized that there are many methods of providing a transform from device independent data to device dependent data, with U.S. Pat. No. 4,275,413 to Sakamoto describing one method, which itself can be varied. Once a conversion table is established, a method of interpolation referred to as tri-linear or cubic interpolation may also be used to calculate output values from the limited set of input values.
To create the table, a set of color patches are created, preferably including determined linearization and black addition. This is done by printing and measuring about 1000 to 4000 patches of printer colors distributed throughout the color space, i.e., a large set of printer driving signals are generated, in varying densities of combinations of C,M,Y,K, or other printer colors and used to drive the printer. The color of each patch is measured, using a spectraphotometer to determine color in terms of Rc,Bc,Gc. The measured colors of these patches are used to build a multidimensional look up table (LUT) relating Rc,Bc,Gc defined colors to Cx Mx Yx defined colors. Conversions that do not include mapped and measured points may be interpolated or extrapolated. Reference is made to U.S. patent application Ser. No. 08/144,987 to Rolleston entitled, "Color Printer Calibration Test Pattern", filed Oct. 29, 1993, which shows and describes a calibration test pattern for this purpose.
With reference again to FIG. 1, a calibration image is conveniently stored in a device memory such as calibration ROM 60, RAM, floppy or the like, or generated on the fly with a predetermined generation function. Signals stored therein are directed to the printer under the control of printer controller 65. Densitometer, spectraphotometer or colorimetrically corrected scanner 70 is used to scan the calibration target and produce Rc, Gc, Bc signal values as a function of sensed density, representing the colors of each scanned patch. Interpatch correlation processor 80 reads the responses provided from densitometer 70 for each location in the calibration target and correlates the response with the input colorant signals, so that an Rc Gc Bc to colorant mapping is generated.
The device independent values may be mapped to the device dependent space, perhaps in a manner described in U.S. Ser. No. 08/223,494 filed Apr. 5, 1994 entitled, "Color Printer Calibration with Improved Color Mapping Linearity". Alternatively the method of Po-Chieh Hung, "Colorimetric Calibration for Scanners and Media", SPIE, Vol. 1448, Camera and Input Scanner System, (1991), which describes a method of inverse tetrahedral interpolation, to the same effect as the described Shepard's Method.
With the look up table derived, it may be stored in LUT and interpolation 40, for use in converting device dependent values received from image creators to device independent printer signals.
In accordance with the invention, if for any reason a second set of mappings of colorimetric values to printer signals is generated, it immediately becomes apparent that one set may be better than the other set. More likely however, is that one set is better than the other set for only a portion of color space. Thus, a desire for optimum reproduction would require that both sets of data be used.
Accordingly, and with reference to FIG. 3, within LUT and Interpolation 40 are multiple look up tables, including a weight table 100, and look up tables LUT1 . . . LUTN, numbered 102. Conveniently, these tables are stored in RAM memory or the like. The tables are in a format that provides the colorimetic color description RC, GC, BC as an index or input value to each table. Coefficient table 100 has as outputs coefficients A1 . . . AN. Each coefficient A1 . . . AN is derivable as a function of the position of the colorimetic color description in color space, and varies with the relative weight to be accorded to the LUT's relationship that region or portion of color space. In one embodiment, there is a set of coefficients A1 . . . AN corresponding to each table LUT1 . . . LUTN. Values are stored to coefficient table 100 and LUT1 . . . LUT from LUT processor 100. Coefficients stored to coefficient table 100 may also be operator or user generated and input to coefficient table 100 from a user interface.
LUT1 . . . LUTN are tables derived through the processes described above for the generation of first color space to second color space conversion. They are also in a format that provides the colorimetic color description RC, GC, BC as an index or input value to each table, but provide, for example, output CMYK signals. The signals are from LUT output respectively to multipliers 1201 . . . 120N which have as a second input a corresponding coefficient A1 . . . AN from Table 100. The output of multipliers 1201 . . . 120N is directed to an adder or accumulator 130 which actually adds the results together and directs its output to another area in memory, LUTNEW 134. From this area in memory, interpolator 140 can receive the stored information to produce its color conversion values. Interpolator 140, using for example trilinear or tetrahedral interpolation (as taught for example in U.S. Pat. No. 4,275,413 to Sakamoto) uses the stored LUT values to derive interpolated output values. (FIG. 3 shows block 40 from FIG. 1, labeled LUT AND INTERPOLATION, and therefore should include the tetrahedral or trilinear interpolation function, which is represented by interpolator 140.)
It can therefore be seen that the plural table blending function is characterized by
LUTNEW (r,g,b)=A1(r,g,b)ŚLUT1(r,g,b)+A2(r,g,b)ŚLUT2(r,g,b)+A3(r, g,b)ŚLUT3(r,g,b)+. . . +AN(r,g,b)ŚLUTN(r,g,b)
A1(r,g,b)+A2(r,g,b)+A3(r,g,b)+. . . +AN(r,g,b)=1
at each location in color space.
It is interesting to note that the case of only two tables, LUT1 and LUT 2 (which is expected to be a common case), can be addressed in a special manner, since if weight A1=A is accorded to LUT1, the weight A2 for LUT 2 is equal 1-A, and accordingly need not be stored independently. The special case of two LUT's can be addressed as:
where LUT1() and LUT2() are the values of the first and second LUT's at some location (i.e. r, g, b) in the table, and A() is a function of the table location such that 0<=A<=1. Of course, this result can be generalized to include N tables with N-1 weights.
In considering the function of position, it is useful to note that the function need not be a linear combination of LUT's. A particularly valuable function may represent use of only a single LUT at any point in space. Thus, within the area best characterized by LUT N, AN=1, while all other LUT's have a value of A=0.
The embodiment described has been illustrated as generating a new LUT, named LUTNEW. However, it is within the scope of the invention to generate blended values from LUT1 . . . LUTN on the fly, without storage or creation of a new LUT. Thus, the output of adder 130 would be directed immediately to interpolator 140, for each value of RC GC BC which is directed to coefficient table 100 and LUT table 102.
It is worth noting that the blending can be performed in any color space or coordinate system, and that the idea is not limited to using a linear combination of the preliminary LUTs. The novel aspect of this invention is the ability to combine several different LUTs into a single LUT. This technique has been reduced to practice, and in the example sighted above, the weights were set such that A=1 at R, G, B C,M,Y and W (i.e., all colors including white), and A=0 at K (black). Intermediate values of A were calculated by interpolation within this cube. LUT1 was the LUT which resulted from using a weighted average, and LUT2 was obtained by using tetrahedral inversion.
It will no doubt be appreciated that while we have shown the use of the invention in the conversion of a device independent color space to a device dependent color space, the invention applies equally as well to conversions to any transformation from a first space to a second space, irrespective of the nature of the space as device dependent or not.
It will no doubt be appreciated that the present invention can be accomplished through application software accomplishing the described functions, though a hardware circuit, which will probably provide optimum speed, or through some combination of software and hardware.
The invention has been described with reference to a particular embodiment. Modifications and alterations will occur to others upon reading and understanding this specification. It is intended that all such modifications and alterations are included insofar as they come within the scope of the appended claims or equivalents thereof.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US2790844 *||May 11, 1954||Apr 30, 1957||Adalia Ltd||Color correction selector|
|US4275413 *||Jul 3, 1979||Jun 23, 1981||Takashi Sakamoto||Linear interpolator for color correction|
|US4500919 *||May 4, 1982||Feb 19, 1985||Massachusetts Institute Of Technology||Color reproduction system|
|US5305119 *||Oct 1, 1992||Apr 19, 1994||Xerox Corporation||Color printer calibration architecture|
|US5331439 *||Feb 17, 1993||Jul 19, 1994||Scitex Corporation Ltd.||Apparatus and method for color transformation|
|US5381246 *||Dec 8, 1993||Jan 10, 1995||Mutoh Industries, Ltd.||Image processing system for converting a full color image into a pseudo-color CMY dot representation|
|1||D. Shepard, "A Two-Dimensional Interpolation Function for Irregularly-Spaced Data", Proceedings-1968 ACM National Conference, pp. 517-524.|
|2||*||D. Shepard, A Two Dimensional Interpolation Function for Irregularly Spaced Data , Proceedings 1968 ACM National Conference, pp. 517 524.|
|3||P. Laihanen, "Colour Reproduction Theory Based on the Principles of Colour Science"; Advances in Printing Science & Technology, W. H. Banks ed, Pentech Press, London 1988, pp. 1-36.|
|4||P. Laihanen, "Optimization of Digital Color Reproduction on the Basis of Visual Assessment of Reproduced Images", Proceedings of the SID, vol. 30, No. 3, 1989, pp. 183-190.|
|5||*||P. Laihanen, Colour Reproduction Theory Based on the Principles of Colour Science ; Advances in Printing Science & Technology, W. H. Banks ed, Pentech Press, London 1988, pp. 1 36.|
|6||*||P. Laihanen, Optimization of Digital Color Reproduction on the Basis of Visual Assessment of Reproduced Images , Proceedings of the SID, vol. 30, No. 3, 1989, pp. 183 190.|
|7||P. Lancaster et al, "Surfaces Generated by Moving Least Squares Methods"; Mathematics of Computation, vol. 32, No. 155, Jul. 1981, pp. 141-158.|
|8||*||P. Lancaster et al, Surfaces Generated by Moving Least Squares Methods ; Mathematics of Computation, vol. 32, No. 155, Jul. 1981, pp. 141 158.|
|9||*||Po Chieh Hung, Colorimetric Calibration for Scanners and Media , SPIE, vol. 1448, Camera and Input Scanner System (1991).|
|10||*||Po Chieh Hung, Tetrahedral Division Technique Applied to Colorimetric Cabibration for Imaging Media , Annual Meeting IS&T, N.J., May 1992, pp. 419 422.|
|11||Po-Chieh Hung, "Colorimetric Calibration for Scanners and Media", SPIE, vol. 1448, Camera and Input Scanner System (1991).|
|12||Po-Chieh Hung, "Tetrahedral Division Technique Applied to Colorimetric Cabibration for Imaging Media", Annual Meeting IS&T, N.J., May 1992, pp. 419-422.|
|13||Sigfredo I. Nin et al, "Printing CIELAB Images on a CMYK Printer Using Tri-Linear Interpolation", SPIE Proceedings, vol. 1670, 1992, pp. 316-324.|
|14||*||Sigfredo I. Nin et al, Printing CIELAB Images on a CMYK Printer Using Tri Linear Interpolation , SPIE Proceedings, vol. 1670, 1992, pp. 316 324.|
|15||William J. Gordon et al, "Shepard's Method of `Metric Interpolation` to Bivariate and Multivariate Interpolation", Mathematics of Computation, vol. 32, No. 141, Jan. 1978, pp. 253-264.|
|16||*||William J. Gordon et al, Shepard s Method of Metric Interpolation to Bivariate and Multivariate Interpolation , Mathematics of Computation, vol. 32, No. 141, Jan. 1978, pp. 253 264.|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US5689350 *||Dec 12, 1994||Nov 18, 1997||Xerox Corporation||Color printer calibration method for accurately rendering selected colors|
|US5734802 *||Feb 29, 1996||Mar 31, 1998||Xerox Corporation||Blended look-up table for printing images with both pictorial and graphical elements|
|US5739927 *||Jun 7, 1995||Apr 14, 1998||Xerox Corporation||Method for refining an existing printer calibration using a small number of measurements|
|US5767980||Jun 20, 1995||Jun 16, 1998||Goss Graphic Systems, Inc.||Video based color sensing device for a printing press control system|
|US5805280||Sep 28, 1995||Sep 8, 1998||Goss Graphic Systems, Inc.||Control system for a printing press|
|US5809213 *||Jul 12, 1996||Sep 15, 1998||Seiko Epson Corporation||Automatic color calibration of a color reproduction system|
|US5812705 *||Jun 2, 1997||Sep 22, 1998||Goss Graphic Systems, Inc.||Device for automatically aligning a production copy image with a reference copy image in a printing press control system|
|US5818613 *||Dec 4, 1995||Oct 6, 1998||Silicon Graphics, Inc.||System and method for color space conversion|
|US5841955||Aug 16, 1995||Nov 24, 1998||Goss Graphic Systems, Inc.||Control system for a printing press|
|US5875028||Sep 12, 1997||Feb 23, 1999||Goss Graphic Systems, Inc.||Workstation for both manually and automatically controlling the operation of a printing press|
|US5903712 *||Oct 5, 1995||May 11, 1999||Goss Graphic Systems, Inc.||Ink separation device for printing press ink feed control|
|US5933256 *||May 14, 1996||Aug 3, 1999||Xexox Corporation||Method for color correction within a color space using hue shifting of a region therein|
|US5946113 *||Mar 29, 1996||Aug 31, 1999||Silicon Graphics, Inc.||System and method for color space conversion|
|US5953499 *||Jun 27, 1997||Sep 14, 1999||Xerox Corporation||Color printing hue rotation system|
|US5978107 *||Aug 2, 1995||Nov 2, 1999||Fuji Xerox Co., Ltd.||Method and apparatus for determining color transformation coefficients|
|US5987168 *||Mar 25, 1997||Nov 16, 1999||International Business Machines Corporation||System, method, and program for converting three dimensional colorants to more than three dimensional colorants|
|US6061501 *||Mar 25, 1997||May 9, 2000||International Business Machines Corporation||System, method and program for converting an externally defined four colorant (CMYK) into an equivalent four dimensional colorant defined in terms of the four inks (C'M'Y'K') that are associated with a given printer|
|US6075886 *||Mar 9, 1998||Jun 13, 2000||Xerox Corporation||Method and apparatus for reducing the complexity of color correction using subsampling|
|US6137594 *||Mar 25, 1997||Oct 24, 2000||International Business Machines Corporation||System, method and program for converting an externally defined colorant CMYK into an equivalent colorant (C'M'Y'K') associated with a given printer|
|US6147698 *||May 29, 1997||Nov 14, 2000||International Business Machines Corporation||Density control for a printer|
|US6160644 *||Mar 30, 1998||Dec 12, 2000||Seiko Epson Corporation||Scanner calibration technique to overcome tone inversion|
|US6178007||Jan 21, 1997||Jan 23, 2001||Xerox Corporation||Method for continuous incremental color calibration for color document output terminals|
|US6181445||Mar 30, 1998||Jan 30, 2001||Seiko Epson Corporation||Device-independent and medium-independent color matching between an input device and an output device|
|US6185004||Mar 30, 1998||Feb 6, 2001||Seiko Epson Corporation||Self-calibration for color image reproduction system|
|US6204939||Mar 30, 1998||Mar 20, 2001||Seiko Epson Corporation||Color matching accuracy inside and outside the gamut|
|US6215562||Dec 16, 1998||Apr 10, 2001||Electronics For Imaging, Inc.||Visual calibration|
|US6222648||Jan 21, 1997||Apr 24, 2001||Xerox Corporation||On line compensation for slow drift of color fidelity in document output terminals (DOT)|
|US6262810||Sep 11, 1997||Jul 17, 2001||Ricoh Corporation||Digital imaging color calibration|
|US6281984||Mar 25, 1997||Aug 28, 2001||International Business Machines Corporation||Enhanced system, method and program for converting an externally defined four dimensional colorant (CMYK) into an equivalent four dimensional colorant defined in terms of the four inks (C′M′Y′K′) that are associated with a given printer|
|US6330078||Dec 9, 1998||Dec 11, 2001||Xerox Corporation||Feedback method and apparatus for printing calibration|
|US6360007||Dec 22, 1998||Mar 19, 2002||Xerox Corporation||Dynamic optimized color lut transformations based upon image requirements|
|US6381037||Jun 28, 1999||Apr 30, 2002||Xerox Corporation||Dynamic creation of color test patterns for improved color calibration|
|US6389161||Aug 16, 1997||May 14, 2002||Heidelberger Druckmaschinen Ag||Method of interpolation in an n-dimensional color space|
|US6404511||Dec 11, 1998||Jun 11, 2002||Seiko Epson Corporation||Self-calibration of network copier system|
|US6421142||Jan 7, 1999||Jul 16, 2002||Seiko Epson Corporation||Out-of-gamut color mapping strategy|
|US6441923||Jun 28, 1999||Aug 27, 2002||Xerox Corporation||Dynamic creation of color test patterns based on variable print settings for improved color calibration|
|US6522427||Sep 21, 1999||Feb 18, 2003||Seiko Epson Corporation||Color table manipulations for contour reduction|
|US6532081||Jul 23, 1999||Mar 11, 2003||Xerox Corporation||Weight calculation for blending color transformation lookup tables|
|US6546132||Sep 21, 1999||Apr 8, 2003||Seiko Epson Corporation||Color table manipulations for smooth splicing|
|US6588879||Dec 3, 2001||Jul 8, 2003||Supersample Corporation||Method for ink jet printing a digital image on a textile, the system and apparatus for practicing the method, and products produced by the system and apparatus using the method|
|US6615729||Nov 14, 2001||Sep 9, 2003||Heidelberger Druckmaschinen Ag||Method and device for determining and/or converting color profiles|
|US6625306||Dec 7, 1999||Sep 23, 2003||Xerox Corporation||Color gamut mapping for accurately mapping certain critical colors and corresponding transforming of nearby colors and enhancing global smoothness|
|US6714319||Dec 3, 1999||Mar 30, 2004||Xerox Corporation||On-line piecewise homeomorphism model prediction, control and calibration system for a dynamically varying color marking device|
|US6809837||Nov 29, 1999||Oct 26, 2004||Xerox Corporation||On-line model prediction and calibration system for a dynamically varying color reproduction device|
|US6864995 *||Feb 27, 2001||Mar 8, 2005||Fuji Photo Film Co., Ltd.||Gradation correction curve producing method, gradation correction curve producing apparatus, and gradation correction curve producing program storage medium|
|US6873432||Nov 30, 1999||Mar 29, 2005||Xerox Corporation||Method and apparatus for representing color space transformations with a piecewise homeomorphism|
|US6882447 *||Oct 12, 2000||Apr 19, 2005||Seiko Epson Corporation||Image converting apparatus, storage medium, and image converting method|
|US6982812||Jan 22, 2001||Jan 3, 2006||Hewlett-Packard Development Company, L.P.||Calibration of printing devices|
|US7072733||Jan 22, 2002||Jul 4, 2006||Milliken & Company||Interactive system and method for design, customization and manufacture of decorative textile substrates|
|US7113307 *||Aug 3, 2000||Sep 26, 2006||Fuji Photo Film Co., Ltd.||Color correction definition producing method, color correction definition producing apparatus, and color correction definition producing program storage medium|
|US7116452||Apr 15, 2002||Oct 3, 2006||Lexmark International, Inc.||Method of calibrating a scanner to a printer|
|US7136187 *||Aug 3, 2000||Nov 14, 2006||Fuji Photo Film Co., Ltd||Color correcting relation extracting method and color correction method|
|US7148900 *||Jun 14, 2001||Dec 12, 2006||Danichisekia Color And Chemicals Mfg. Co., Ltd.||CCM calculating system, CCM calculating method and recording medium|
|US7152941||Oct 28, 2003||Dec 26, 2006||Hewlett-Packard Development Company, L.P.||Printing system calibration|
|US7411700||Oct 28, 2003||Aug 12, 2008||Hewlett-Packard Development Company, L.P.||Printing system calibration|
|US7427115||Mar 28, 2002||Sep 23, 2008||Xerox Corporation||Fluid ejector including a drop size symbol, a method of disposing a drop size symbol in a fluid ejector, and an image forming device including a marking fluid ejector with a drop size symbol|
|US7450281 *||Apr 23, 2003||Nov 11, 2008||Canon Kabushiki Kaisha||Image processing apparatus and information processing apparatus, and method thereof|
|US7522354||Feb 5, 2007||Apr 21, 2009||Uni-Pixel Displays, Inc.||Enhancing a field sequential color palette in an optical display|
|US7524006||May 1, 2008||Apr 28, 2009||Xerox Corporation||Fluid ejector including a drop size symbol, a method of disposing a drop size symbol in a fluid ejector, and an image forming device including a marking fluid ejector with a drop size symbol|
|US7564602 *||Jul 27, 2004||Jul 21, 2009||Hoya Corporation||Color chart for adjustment of a color printer and a color monitor utilized with an endoscope|
|US7669948||May 1, 2008||Mar 2, 2010||Xerox Corporation||Fluid ejector including a drop size symbol, a method of disposing a drop size symbol in a fluid ejector, and an image forming device including a marking fluid ejector with a drop size symbol|
|US7684084||Sep 25, 2007||Mar 23, 2010||Xerox Corporation||Multiple dimensional color conversion to minimize interpolation error|
|US7706036||Nov 12, 2002||Apr 27, 2010||Seiko Epson Corporation||Color conversion program, apparatus, and method enabling high precision color conversion|
|US7783126||Sep 10, 2004||Aug 24, 2010||Panasonic Corporation||Visual processing device, visual processing method, visual processing program, and semiconductor device|
|US7813014 *||Oct 1, 2003||Oct 12, 2010||Heidelberger Druckmaschinen Ag||Method of adapting a printing process while maintaining black build-up|
|US7860339||Sep 10, 2004||Dec 28, 2010||Panasonic Corporation||Visual processing device, visual processing method, visual processing program, intergrated circuit, display device, image-capturing device, and portable information terminal|
|US7864366 *||Sep 11, 2007||Jan 4, 2011||Xerox Corporation||Method and system for improved space filling interpolation|
|US7880942||Mar 7, 2006||Feb 1, 2011||Adobe Systems Incorporated||Method and apparatus for converting color coefficients between color spaces|
|US7945115||Jul 19, 2010||May 17, 2011||Panasonic Corporation||Visual processing device, visual processing method, visual processing program, and semiconductor device|
|US7990588||Dec 12, 2006||Aug 2, 2011||Canon Kabushiki Kaisha||Method of finding look-up table structures in color device sampling data|
|US8014057||Sep 6, 2011||Rambus Inc.||Extending the gamut color generation in a display|
|US8077376||May 15, 2008||Dec 13, 2011||Rambus Inc.||Visible plus non-visible field sequential color|
|US8134547 *||Jul 22, 2008||Mar 13, 2012||Xerox Corporation||Merit based gamut mapping in a color management system|
|US8165417||Oct 31, 2007||Apr 24, 2012||Panasonic Corporation||Visual processing device, visual processing method, visual processing program, integrated circuit, display device, image-capturing device, and portable information terminal|
|US8330991||Mar 3, 2009||Dec 11, 2012||Columbia Insurance Company||Method for managing metamerism of color merchandise|
|US8379267||Dec 3, 2009||Feb 19, 2013||Xerox Corporation||Method to retrieve a gamut mapping strategy|
|US8467090||Mar 3, 2009||Jun 18, 2013||Columbia Insurance Company||Color selection apparatus and method for producing low metameric color merchandise|
|US8488192||Apr 29, 2010||Jul 16, 2013||Xerox Corporation||Method for mapping an out-of-gamut color using a reference gamut mapping|
|US8649063 *||Dec 7, 2012||Feb 11, 2014||Samsung Electronics Co., Ltd.||Image forming apparatus and method thereof to generate a new image mode by combining selected image modes|
|US20010033387 *||Feb 27, 2001||Oct 25, 2001||Masaki Nogiwa||Gradation correction curve producing method, gradation correction curve producing apparatus, and gradation correction curve producing program storage medium|
|US20010052904 *||Jun 14, 2001||Dec 20, 2001||Dainichiseika Color & Chemicals Mfg Co., Ltd||CCM calculating system, CCM calculating method and recording medium|
|US20020103719 *||Jan 30, 2002||Aug 1, 2002||Beedy Jennifer L.||Color change method and product|
|US20020180998 *||Jun 5, 2001||Dec 5, 2002||Yifeng Wu||Methods and arrangements for calibrating a color printing device using multi-dimensional look-up tables|
|US20030139840 *||Jan 22, 2002||Jul 24, 2003||Ronald Magee||Interactive system and method for design, customization and manufacture of decorative textile substrates|
|US20030184810 *||Mar 28, 2002||Oct 2, 2003||Xerox Corporation||First and second methods for an image forming device to form an image based on a drop size symbol|
|US20030193678 *||Apr 15, 2002||Oct 16, 2003||Yao Han||Method of calibrating a scanner to a printer|
|US20030202194 *||Apr 23, 2003||Oct 30, 2003||Makoto Torigoe||Image processing apparatus and information processing apparatus, and method therefor|
|US20040136018 *||Oct 1, 2003||Jul 15, 2004||Uwe-Jens Krabbenhoft||Method of adapting a printing process while maintaining black build-up|
|US20050024658 *||Jul 27, 2004||Feb 3, 2005||Pentax Corporation||Color chart|
|US20050088672 *||Oct 28, 2003||Apr 28, 2005||Johnson David A.||Printing system calibration|
|US20050174586 *||Nov 12, 2002||Aug 11, 2005||Seishin Yoshida||Color coversion apparatus color conversion method color change program and recording medium|
|US20060041609 *||Aug 20, 2004||Feb 23, 2006||Pellar Ronald J||System and method for multi-dimensional lookup table interpolation|
|US20070109447 *||Sep 10, 2004||May 17, 2007||Haruo Yamashita||Visual processing device, visual processing method, visual processing program, and semiconductor device|
|US20070150813 *||Feb 5, 2007||Jun 28, 2007||Uni-Pixel Displays, Inc.||Extending the Gamut Color Generation in an Optical Flat Panel Display|
|US20070188623 *||Sep 10, 2004||Aug 16, 2007||Haruo Yamashita||Visual processing device, visual processing method, visual processing program, intergrated circuit, display device, image-capturing device, and portable information terminal|
|US20080107360 *||Oct 31, 2007||May 8, 2008||Haruo Yamashita||Visual processing device, visual processing method, visual processing program, integrated circuit, display device, image-capturing device, and portable information terminal|
|US20080130023 *||Oct 28, 2004||Jun 5, 2008||Hewlett-Packard Development Company, L.P.||Color Reproduction on Translucent or Transparent Media|
|US20080137112 *||Dec 12, 2006||Jun 12, 2008||Canon Kabushiki Kaisha||Method of finding look-up table structures in color device sampling data|
|US20080177777 *||Sep 25, 2007||Jul 24, 2008||Kazuhiro Osaki||Database management method, program thereof and database management apparatus|
|US20080297547 *||May 1, 2008||Dec 4, 2008||Xerox Corporation|
|US20080303850 *||May 1, 2008||Dec 11, 2008||Xerox Corporation|
|US20090066978 *||Sep 11, 2007||Mar 12, 2009||Xerox Corporation||Method and system for improved space filling interpolation|
|US20100177332 *||Mar 19, 2010||Jul 15, 2010||Heidelberger Druckmaschinen Ag||Method of adapting a printing process while maintaining black build-up|
|DE19641822A1 *||Oct 10, 1996||Apr 16, 1998||Hell Ag Linotype||Verfahren zur Interpolation in einem n-dimensionalen Farbraum|
|EP0887999A2 *||Jun 8, 1998||Dec 30, 1998||Xerox Corporation||Color printing method and apparatus|
|EP1445941A1 *||Nov 12, 2002||Aug 11, 2004||Seiko Epson Corporation||Color conversion device, color conversion method, color change program and recording medium|
|EP2384904A1||May 4, 2010||Nov 9, 2011||Benjamin Moore&Co.||Apparatus and method for dispensing color merchandise|
|U.S. Classification||358/518, 358/504, 358/523, 358/501|
|International Classification||B41J2/525, G03G15/00, G03G15/01, H04N1/40, G03F3/08, H04N1/46, H04N1/60|
|Cooperative Classification||H04N1/40006, H04N1/6033|
|European Classification||H04N1/40A, H04N1/60F2|
|Jun 6, 1994||AS||Assignment|
Owner name: XEROX CORPORATION, CONNECTICUT
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ROLLESTON, ROBERT J.;MALTZ, MARTIN S.;REEL/FRAME:007026/0078
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Owner name: BANK ONE, NA, AS ADMINISTRATIVE AGENT, ILLINOIS
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